1. Field of the Invention
The present invention relates to a car audio system, more particularly, to an integrated circuit (hereinafter referred to as "IC") type car audio system capable of being operated at a general mode or an IC card mode and an operating method thereof.
2. Description of the Prior Art
In general, a car audio system is installed on a control panel of all kinds of vehicles and serves to provide broadcasting or music to passengers therein. Since the car audio system is expensive and can be easily detached from the control panel, it has become the object of theft. In order to solve the above problems, a password number input device of a car audio system has been proposed.
FIG. 1 shows a conventional password number input device 10 of a car audio system. The conventional password number input device 10 of a car audio system includes a key input section 102 for inputting a password number, a decoder 104 for receiving the password number from the key input section 102 and converting the password number into a binary data signal, a microcomputer 106 for receiving the binary data signal from the decoder 104 and outputting a control signal based on the received binary data signal, and a memory 108 for storing the password number under control of the microcomputer 106.
An operation of the conventional password number input device 10 of the audio system will now be described. When a user inputs a password number by use of the key input section 102, the password number is inputted to the decoder 104. The decoder 104 receives the password number from the key input section and converts it into a binary data signal. The binary data signal is applied to the microcomputer 106. Accordingly, the microcomputer 106 receives the password number which is converted into the binary data signal from the decoder 104, outputs a write signal to the memory 108 and designates a corresponding address in the memory 108, and controls the memory 108 to store the password number in the designated address thereof.
In the conventional password input device 10 of the car audio system, a user should remember the password number. Further, since the user should input the password number every time he uses the car audio system, it is extremely inconvenient.
U.S. Pat. No. 5,285,055 (issued to Satoru Oonakahara and Murayama on Feb. 8, 1997) discloses IC card containing a CPU and a memory, for storing seat reservation data and read/write control method for controlling the operation of reading out data stored in a memory contained in the IC card and writing data into the memory. In the conventional IC card, a plurality of password numbers are previously stored and data can be read out from the IC card and written into the IC card when any one of the plurality of password numbers is input. Further, data readout and write-in with respect to the IC card are partially limited according to the input password number.